THE WOUNDS ARE STILL FRESH from 1990, when Measure B went down to decisive defeat, as did its counterpart in Marin. Those ballot initiatives sought to finance a series of transit improvements, but failed decisively, in part because the Sonoma County environmental community balked at the low priority that rail transit was given in the overall package.

Now, with the prospect of a new initiative going before the voters in 1998, a coalition of business, political, and environmental interests are cautiously trying to stake out common ground, despite some deep-seated distrust.

The common goal is voter approval of a half-cent sales tax hike, which is projected to raise approximately $433 million in Sonoma County over its 18-year lifespan. A matching tax increase in Marin would generate another $251 million. Combined, that would be enough to pay for the entire list of transportation improvements flagged in the Calthorpe study, which are estimated to cost about $655 million.

But Calthorpe's recommendations and the list that will be formally linked with any future ballot measures may be significantly different, the result of extensive behind-the-scenes wrangling and deal-cutting. Even the question of who will make those decisions has been heatedly debated. When environmental and business leaders suggested last spring that the politicians stand aside, as happened when a model measure passed in Santa Clara County last year, county supervisors quickly scuttled the notion. They insisted that the Sonoma County Transportation Authority, whose members are all local elected officials, be included in the campaign, and a compromise was soon announced.

Meanwhile, in Marin, the most skeptical voices are coming from the environmental community. "Our concern is that the [Calthorpe] study didn't say anything about the environmental benefits of any of the components," says Joy Dahlgren, chair of the Marin Conservation League's Transportation Committee. "There are some environmental costs to the rail and the highway."

Dahlgren fears that rail could have greater negatives in Marin, where most of Highway 101 is already six lanes wide. "If the rail system could be shown to have a net environmental benefit and total benefits greater than its cost, and if there was a guarantee that money would not be diverted from the current bus service, and that it included maintenance of local streets and roads, we could probably support it," Dahlgren says. "It's not going to eliminate congestion, but I do think the train will eliminate pressure for freeway expansion.

"But I don't think that many people will use it. There's a bus service now, but not that many use it."

Unlike their counterparts to the south, Sonoma County environmental leaders are lined up firmly behind the transit tax concept. Here, resistance is strongest from the business and development interests.

"There are some who are so enamored of rail that they will resist any improvement to the infrastructure unless rail is included," grumbles Bob Harder of the North Coast Builders Exchange. "To make rail workable, you need riders, enough riders to cover the cost, so the citizenry isn't subsidizing it abnormally.

"There is a significant question of whether a county of half a million people, spread out as we are, is ever going to make rail pay."

The assumption that passenger-rail service can be economically self-sufficient is simply wrong, says Supervisor Jim Harberson. Rail offers other benefits to justify subsidies, he contends. "It helps keep people off the freeway, helps air quality, and helps congestion," Harberson says. "But it won't make money."

Mark Green of Sonoma County Conservation Action has other reasons to be wary of the fragile consensus that has developed around the Calthorpe study. "We're happy that in word, if not in deed, the business community has signed on the Calthorpe plan," Green says guardedly. "We're just waiting to see what the ballot measure looks like."

Green worries that the general support for rail is "mostly window dressing to entice voters," while the measure placed before the electorate will seek the tax increase for too short a time to pay for all the proposed transportation improvements, such as the nine-year interval under discussion. If highway projects eat up all of the dollars, and a second ballot measure is needed to generate the funds to build the rail system, "my guess is that the business community would jump up and down and say, 'Hell no, we don't want to pay anymore. We already got our freeway widened,' " Green says.

Supervisor Mike Cale, an ardent booster of the highway/rail combination, is among those who feel that two ballot measures may be preferable. "I would think that doing two nine-year ballot measures has a far better chance for success than a 20-year one," he offers. He acknowledges that "the fear from the rail proponents is that they'll get left high and dry."

To overcome that mistrust, Cale says, "Trust bubbles are going to have to be floated up pretty high."

Although Green remains wary, he is willing to negotiate. "I believe there are people who are willing to flex on this issue," he says hopefully, "so we can still be together for 1998."

And perspective is important, Harder adds. "They're not voting for the tax or paradise; they're voting for the tax or a continuation of the deterioration of the quality of life."